Old Res Weather

Lexington, Massachusetts, USA

35°F

2/16/2025 7:17pm

Lexington Conditions: Clear
Temperature: 35.1°F / 1.7°C
Dew Point: 32.4°F
Relative Humidity: 90%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.00 in Falling Slowly
Visibility: 10 miles
Rain Today: 0.01 in
UV Index: $VPuv None

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 080805
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
405 AM EDT Sat Aug 8 2026

.WHAT HAS CHANGED...
Forecast remains on track.

&&

.KEY MESSAGES...

- Diurnal shower and thunderstorm chances remain a threat today.
  Heat and Humidity remain elevated, but slowly trending down
  compared to the last few days.

- Very warm and humid weather continues through Wednesday.
  Daily shower and storm chances each day too, but lesser of a
  chance Sunday.

- Turning much less humid with cooler temperatures late this 
  week.

&&

.DISCUSSION...
KEY MESSAGE 1...Diurnal shower and thunderstorm chances remain 
a threat today. Heat and Humidity remain elevated, but slowly 
trending down compared to the last few days.

The overall upper-level pattern becomes more zonal this 
weekend; however, another quick moving shortwave will be the 
catalyst for another round of showers and thunderstorms this 
afternoon and evening. Much like the last few days, CAM guidance
isn't handling the environment well. Uncertainty remains high 
in where and when storms could initiate this afternoon as well 
as how far east they'll travel. However, the 00z runs of both 
CSU's ML guidance and the HRRR Neural Network indicate higher 
confidence that some severe storms could pop over interior 
southern New England. Given dewpoints will once again be in the 
low to mid 70s, PWATs will likely be in the 1.75"-2.00" range. 
Latest guidance suite also indicates that the mid- level 
steering flow could be a little faster than we've seen over the 
last few days. This indicates that while there could be heavy 
downpours/torrential rainfall within storms, they will likely be
moving a little faster than we've seen previously and less 
likely to train. Latest model soundings also indicate higher 
DCAPE values (ranging from 600-1,000 depending on the model) 
across portions of western MA and CT. Both CSU's ML 
probabilities and the HRRR's Neural Network also show 15%-30% 
probs of severe winds draped across the Hartford-Worcester-
Lowell corridor.

Regardless, any thunderstorms that do pop both today have the 
potential to produce frequent lightning, gusty winds, and 
torrential downpours, and we can't rule out localized flash 
flooding if a storm or two were to push over a more vulnerable 
area (urban/poor drainage, area of recent heavy rainfall).

KEY MESSAGE 2...Very warm and humid weather continues through 
Wednesday. Daily shower and storm chances each day too, but 
lesser of a chance Sunday.

Overall pretty persistent summer weather pattern really right 
through Wednesday, with enhanced quasi-zonal flow in midlevels 
interacting with summerlike temperatures and humidity levels. 

Warm temperatures and elevated but not really oppressive 
humidity levels (dewpoints in the mid to upper 60s) can be 
expected to continue through Wednesday. General sameness to 
925-850 mb temps each day, only slightly cooling by a degree or 
two from Sunday through Wednesday, which supports highs in the 
mid/upper 80s and heat indices in the lower to middle 90s. While
not necessarily a hazardous combo of heat and humidity and most
are already acclimatized to the summer warmth, thus not looking
at headline- level heat, it is still an extended spell of heat 
indices in the low to mid 90s, so still continue to adequately 
hydrate and take breaks in cooler spaces.

With westerly mostly non-convergent low-level flow and modest 
height rises Sunday, Sunday should end up being a generally dry 
day as will be tough to get enough lift to spark storms. 
Otherwise, daily shower and thunderstorm chances again resume 
for early to mid next week, and with somewhat stronger flow, a 
couple of those storms could become strong or severe in this 
timeframe. The issue is timing the storms out, as has been the 
case most of this week; this is very challenging as any ripple 
in the faster mid-level flow could focus better storm chances 
given the warm and humid weather. At this forecast time horizon 
timing specific day(s) have more storm chances than others is a 
tough ask. Won't be raining and thundering all the time but 
there will be storms to dodge here-and-there. 

Tough to find many areas to improve upon NBM so stayed fairly 
close to outputted NBM forecast values during this period.

KEY MESSAGE 3...Turning much less humid with cooler 
temperatures late this week. 

The true "break of the heat and humidity" takes place late in 
the week, as we become more entrenched in cyclonic flow aloft 
with northwest winds bringing both temps and dewpoints down to 
more seasonable levels. Highs closer to the upper 70s to lower 
80s; wouldn't rule out a spot shower or two under the cyclonic 
flow but nothing that looks necessarily significant. 

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...

Low - less than 30 percent. 
Moderate - 30 to 60 percent. 
High - greater than 60 percent.

06Z TAF Update: 

Today through Tonight: Overall high confidence, but lower on 
TSRA timing.

Patchy MVFR/IFR stratus/fog along the south 
coast/Cape/Islands/CT River Valley improves this morning to VFR.
Generally WSW winds today, with some gusts near 20 kts along 
the Cape/Islands. Still some uncertainty in timing of TSRA, 
which again varies between 18-20z at earliest to as late as 01z,
then moving eastward. PROB30s remain, but pushed 1-2 hours 
later than originally anticipated. TSRA dissipates late this 
evening, with south-coastal fog/stratus returning with VFR 
elsewhere. 

KBOS Terminal...SW winds around 5 kt for most of the day. 
Seabreeze not likely today. Monitoring for TSRA this 
aftn/evening but not likely any sooner than 21z if they get 
close.

KBDL Terminal...Moderate confidence. Generally VFR. Another 
risk for TSRA this aftn/evening, but exact timing is still 
uncertain.

Outlook /Sunday through Wednesday/...

Sunday: VFR. Breezy. 

Sunday Night through Monday: VFR. 

Monday Night: VFR. Slight chance SHRA, slight chance TSRA.

Tuesday: VFR. Breezy. Slight chance SHRA, slight chance TSRA.

Tuesday Night: VFR. Slight chance SHRA.

Wednesday: VFR. Slight chance SHRA, slight chance TSRA.

&&

.MARINE...
Forecaster Confidence Levels...

Low - less than 30 percent. 
Moderate - 30 to 60 percent. 
High - greater than 60 percent.

Through Sunday... High Confidence.

High pressure remains positioned off of the east coast. This 
will continue to produce a SW flow across the entire region into
the weekend. Gusts to 20 kts possible over the southern waters 
today, but should remain under SCA levels.

Outlook /Sunday through Wednesday/...

Sunday through Sunday Night: Winds less than 25 kt. Areas of
seas approaching 5 ft. 

Monday: Winds less than 25 kt. 

Monday Night through Tuesday: Winds less than 25 kt. Slight
chance of rain showers. 

Tuesday Night: Winds less than 25 kt. Chance of rain showers. 

Wednesday: Winds less than 25 kt. Slight chance of rain
showers. 

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

DISCUSSION...Loconto/McMinn
AVIATION...McMinn
MARINE...McMinn